The prior art in the field of the invention has been disclosed in patent publications EP 0418304 B1, EP 0956634 B1 and US 2004/0051416 A1. Known from the publications are rotors of high speed machines provided with permanent magnets which are efficient, but relatively fragile, consisting of rare earth metals. Due to the mechanical properties of the magnets, they are enclosed within a magnetically non-conducting tube or sleeve. The magnet may be fastened centrally in the sleeve with an interference fit, or it is also possible to manufacture the magnet directly inside the sleeve from a powder. Then, axle end pieces are generally fastened with an interference fit at both ends of the sleeve and welded together with the sleeve for greater securement.
The structures disclosed above work, but they encompass several disadvantages particularly in terms of manufacture. Due to many interference fits, it is difficult to assemble the structure, which requires special tools. The welding used for the structures makes them disposable, i.e. they cannot be disassembled without damaging the structures. In addition, it is impossible to modify them for different size classes due to the fixed structure. Furthermore, the setup of the assembly is problematic due to many successive interference fits. Further, it is difficult to fit the axles with bearings in the axial direction, which requires complex structures.